Ion-exchange polymers

ABSTRACT

Ion-Exchange polymers for a polymer electrolyte membrane include a moiety of formula (I), and/or a moiety of formula (II), and/or a moiety of formula (III) wherein at least some of the units I, II and/or III are sulphonated. The phenyl moieties in units I, II, and III are independently optionally substituted and optionally cross-linked; m, r; s, t, v, w and z independently represent zero or a positive integer, E and E′ independently represent an oxygen or a sulphur atom or a direct link, G represents an oxygen or sulphur atom, a direct link or a —O—Ph—O— moiety where Ph represents a phenyl group and Ar is selected from one of the moieties (i) to (x) as set forth herein which is bonded via one or more of its phenyl moieties to adjacent moieties.

This invention relates to ion-exchange polymers and particularly,although not exclusively, relates to sulphonaced polymers, for examplesulphonated polyaryletherketones, polyarylethersulphones and/orcopolymers of the aforesaid. Preferred embodiments of the inventionrelate to ion-conductive membranes, for example of polymer electrolytemembrane fuel cells, made using such polymers. The invention alsorelates to novel, non-sulphonated polyaryletherketones and/orpolyarylethersulphones used for preparing said sulphonated polymers andprocesses for the preparation of polymers described herein.

BACKGROUND OF THE INVENTION

A polymer electrolyte membrane fuel cell (PEMFC), shown schematically inFIG. 1 of the accompanying diagrammatic drawings, may comprise a thinsheet 2 of a hydrogen-ion conducting Polymer Electrolyte Membrane (PEM)sandwiched on both sides by a layer 4 of platinum catalyst and anelectrode 6. The layers 2, 4, 6 make up a Membrane Electrode Assembly(MEA) of less than 1 mm thickness.

In a PEMFC, hydrogen is introduced at the anode (fuel electrode) whichresults in the following electrochemical reaction:

Pt-Anode (Fuel Electrode) 2H₂→4H⁺+4e

The hydrogen ions migrate through the conducting PEM to the cathode.Simultaneously, an oxidant is introduced at the cathode (oxidantelectrode) where the following electrochemical reaction takes place:

 Pt-Cathode (Oxidant Electrode) O₂ +4H⁺+4e→2H₂O

Thus, electrons and protons are consumed to produce water and heat.Connecting the two electrodes through an external circuit causes anelectrical current to flow in the circuit and withdraw electrical powerfrom the cell.

U.S. Pat. No. 5,561,202 (Hoechst) discloses the production of PEMs fromsulphonated aromatic polyether ketones. At least 5% of the sulphonicgroups in the sulphonic acid moieties are converted into sulphonylchloride groups and then reacted with an amine containing at least onecross-linkable substituent or a further functional group. An aromaticsulphonamide is, then isolated, dissolved in an organic solvent,converted into a film and then the cross-linkable substituents in thefilm are cross-linked. The invention is said to provide ion-conductivemembranes suitable for use as polymeric solid electrolytes which haveadequate chemical stability and can be produced from polymers which aresoluble in suitable solvents.

One problem associated with known PEMFCs is that of providing PEMs whichhave desirable properties at elevated temperatures and which are cheapto manufacture.

SUMMARY OF THE INVENTION

It is an object of the present invention to address problems associatedwith PEMs.

According to a first aspect of the invention, there is provided apolymer electrolyte membrane which includes a polymer having a moiety offormula

and/or a moiety of formula

and/or a moiety of formula

wherein at least some of the units I, II and/or III are sulphonated;wherein the phenyl moieties in units I, II, and III are independentlyoptionally substituted and optionally cross-linked; and whereinm,r,s,t,v,w and z independently represent zero or a positive integer, Eand E′ independently represent an oxygen or a sulphur atom or a directlink, G represents an oxygen or sulphur atom, a direct link or a—O—Ph—O— moiety where Ph represents a phenyl group and Ar is selectedfrom one of the following moieties (i) to (x) which is bonded via one ormore of its phenyl moieties to adjacent moieties

The invention extends to a polymer electrolyte membrane which includes apolymer having a moiety of formula I and/or a moiety of formula IIand/or a moiety of formula III as described according to said firstaspect, wherein at least some of units I, II and/or III arefunctionalised to provide ion exchange sites. Suitably, to provide saidion exchange sites, said polymer is sulphonated, phosphorylated,carboxylated, quaternary-aminoalkylated or chloromethylated, andoptionally further modified to yield —CH₂PO₃H₂, —CH₂NR₃ ²⁰⁺ where R²⁰ isan alkyl, or —CH₂NAr₃ ^(x+) where Ar^(x) is an aromatic (arene), toprovide a cation or: anion exchange membrane. Further still, thearomatic moiety may contain a hydroxyl group which can be readilyelaborated by existing methods to generate —OSO₃H and —OPO₃H₂ cationicexchange sites on the polymer. Ion exchange sites of the type stated maybe provided as described in WO95/08581.

References to sulphonation include a reference to substitution with agroup —SO₃M wherein M stands for one or more elements selected with dueconsideration to ionic valencies from the following group: H, NR₄ ^(y+),in which R^(y) stands for H, C₁-C4 alkyl, or an alkali or alkaline earthmetal or a metal of sub-group 8, preferably H, NR₄ ^(y+), Na, K, Ca, Mg,Fe, and Pt. Preferably M represents H. Sulphonation of the type statedmay be provided as described in WO96/29360.

Unless otherwise stated in this specification, a phenyl moiety may have1,4- or 1,3-, especially 1,4-, linkages to moieties to which it isbonded.

Said polymer may include more than one different type of repeat unit offormula I; more than one different type of repeat unit of formula II;and more than one different type of repeat unit of formula III.

Said moieties I, II and III are suitably repeat units. In the polymer,units I, II and/or III are suitably bonded to one another—that is, withno other atoms or groups being bonded between units I, II, and III.

Where the phenyl moieties in units I, II or III are optionallysubstituted, they may be optionally substituted by one or more halogen,especially fluorine and chlorine, atoms or alkyl, cycloalkyl or phenylgroups. Preferred alkyl groups are C₁₋₁₀, especially C₁₋₄, alkyl groups.Preferred cycloalkyl groups include cyclohexyl and multicyclic groups,for example adamantyl. In some cases, the optional substituents may beused in the cross-linking of the polymer. For example, hydrocarbonoptional substituents may be functionalised, for example sulphonated, toallow a cross-linking reaction to take place. Preferably, said phenylmoieties are unsubstituted.

Another group of optional substituents of the phenyl moieties in unitsI, II or III include alkyls, halogens, C_(y)F_(2y+1), where y is aninteger greater than zero, O—R^(q) (where R^(q) is selected from thegroup consisting of alkyls, perfluoralkyls and aryls), CF═CF₂, CN, NO₂and OH. Trifluormethylated phenyl moieties may be preferred in somecircumstances.

Where said polymer is cross-linked, it is suitably cross-linked so as toimprove its properties as a polymer electrolyte membrane, for example toreduce its swellability in water. Any suitable means may be used toeffect cross-linking. For example, where E represents a sulphur atom,cross-linking between polymer chains may be effected via sulphur atomson respective chains. Alternatively said polymer may be cross-linked viasulphonamide bridges as described in U.S. Pat. No. 5,561,202. A furtheralternative is to effect cross-linking as described in EP-A-0008895.

However, for polymers according to the first aspect or second aspectwhich are crystalline (which some are) there may be no need to effectcross-linking to produce a material which can be used as a polymerelectrolyte membrane. Such polymers may be easier to prepare: thancross-linked polymers. Thus, said polymer of the first and/or secondaspects may be crystalline. Preferably, said polymer is not optionallycross-linked as described.

Where w and/or z is/are greater than zero, the respective phenylenemoieties may independently have; 1,4- or 1,3-linkages to the othermoieties in the repeat units of formulae II and/or III. Preferably, saidphenylene moieties have 1,4- linkages.

Preferably, the polymeric chain of the polymer does not include a —S—moiety. Preferably, G represents a direct link.

Suitably, “a” represents the mole % of units of formula I in saidpolymer, suitably wherein each unit I is the same; “b” represents themole % of units of formula II in said polymer, suitably wherein eachunit II is the same; and “c” I represents the mole % of units of formulaIII in said polymer, suitably wherein each unit III is the same.Preferably, a is in the range 45-100, more preferably in the range45-55, especially in the range 48-52. Preferably, the sum of b and c isin the range 0-55, more preferably in the range 45-55, especially in therange 48-52. Preferably, the ratio of a to the sum of b and c is in therange 0.9 to 1.1 and, more preferably, is about 1. Suitably, the sum ofa, b and c is at least 90, preferably at least 95, more preferably atleast 99, especially about 100. Preferably, said polymer consistsessentially: of moieties I, II and/or III.

Said polymer may be a homopolymer having a repeat unit of generalformula

or a homopolymer having a repeat unit of general formula.

or a random or block copolymer of at least two different units of IVand/or V

wherein A, B. C and D independently represent 0 or 1 and E,E′,G,Ar,m,r,s,t,v,w and z are as described in any statement herein.

As an alternative to a polymer comprising units IV and/or V discussedabove, said polymer may be a homopolymer having a repeat unit of generalformula

or a homopolymer having a repeat unit of general formula

or a random or block copolymer of at least two different units of IV*and/or V*, wherein A, B, C, and D independently represent 0 or 1 and E,E′, G, Ar, m, r, s, t, v, w and z are as described in any statementherein.

Preferably, m is in the range 0-3, more preferably 0-12, especially 0-1.Preferably, r is in the range 0-3, more preferably 0-2, especially 0-1.Preferably t is in the range 0-3, more preferably 0-2, especially 0-1.Preferably, s is 0 or 1. Preferably v is 0 or 1. Preferably, w is 0or 1. Preferably z is 0 or 1.

Preferably Ar is selected from the following moieties (xi) to (xxi):

Preferably, (xv) is selected from a 0.1,2-, 1,3-, or a 1,5-moiety; (xvi)is selected from a 1,6-, 2,3-, 2,6- or a 2,7-moiety; and (xvii) isselected from a 1,2-, 1,4-, 1,5-, 1,8- or a 2,6- moiety.

One preferred class of polymers may include at least some ketonemoieties in the polymeric chain. In such a preferred class, the polymerpreferably does not! only include —O— and —SO₂— moieties between aryl(or other unsaturated) moieties in the polymeric chain. Thus, in thiscase, suitably, a polymer of the first and/or second aspects does notconsist only of moieties of formula; III, but also includes moieties offormula I and/or II.

One preferred class of polymers does not include any moieties of formulaIII, but suitably only includes moieties of formulae I and/or II. Wheresaid polymer is a homopolymer or random or block copolymer as described,said homopolymer or copolymer suitably includes a repeat unit of generalformula IV. Such a polymer may, in some embodiments, not include anyrepeat unit of general formula V.

Referring to formula IV, preferably, said polymer is not a polymerwherein: Ar represents moiety (iv), E and E′ represent oxygen atoms, mrepresents zero, w represents 1, s represents zero, and A and Brepresent 1; Ar represents moiety (i), E and E′ represent oxygen atoms,G represents a direct link, m represents zero, w represents 1, rrepresents O, s represents 1 and A and B represent 1; A Ar representsmoiety (iv), E and E′ represent oxygen atoms, G represents a directlink, m represents O, w represents O, s represents 1, r represents 1 andA and B represents 1. Referring to formula V, preferably Ar representsmoiety (iv), E and E′ represent oxygen atoms, G represents a directlink, m represents zero, z represents 1, v represents zero and C and Drepresent 1.

Preferably, said polymer is not a sulphonated aromatic polyecherketoneof formula

—[[Ph—O]_(p)—Ph—[[CO—Ph′]_(x)—O—Ph]_(h)—[CO—Ph′]_(y)—[O—Ph]_(n)—CO—]—

where Ph represents a 1,4- or 1,3-phenylene moiety; Ph′ representsphenylene, naphthylene, biphenylene or anthrylene; p is 1, 2, 3 or 4; x,h and n are, independently, zero or 1; and y is 1, 2 or 3.

Preferably, said polymer does not conform to the formula

where

e is from 0.2 to 1,

f is from 0 to 0.8, and

e+f=1

Preferably, said polymer does not conform to the formula

in which e is a number from 0 to 1, g is a number from 0 to 1, f is anumber from 0 to 0.5, and the sum e+f+g=1.

Preferably, said polymer is not a copolymer built up from at least twodifferent units of formulae:

Suitable moieties Ar are moieties (i), (ii) (iv) and (v) and, of these,moieties (i), (ii) and (iv) are preferred. Preferred moieties Ar aremoieties (xi), (xii), (xiv), (xv) and (xvi) and, of these, moieties(xi), (xii) and (xiv) are especially preferred. Another preferred moietyis moiety (v), especially, moiety (xvi). In relation, in particular tothe alternative polymers comprising units IV* and/or V*, preferred Armoieties are (v) and, especially, (xvi).

Preferred polymers include an electron-rich, relatively non-deactivated,easily sulphonatable unit, for example a multi-phenylene moiety or afused-rings aromatic moiety, such-as naphthalene. Such an easy tosulphonate unit may be sulphonated under relatively mild conditions tointroduce two sulphonate groups per unit. Thus, preferred polymers mayhave at least 10_(n) electrons in a delocalized aromatic moiety. Thenumber of 90 electrons may be 12 or less. Preferred polymers include abiphenylene moiety. Other preferred polymers include a naphthalenemoiety. Preferred polymers include said electron rich, non-deactivated,easily sulphonatable unit bonded to two oxygen atoms. Especiallypreferred polymers include a —O-biphenyllene-O— moiety. especiallypreferred polymers include a —O-naohthalene-O— moiety.

Preferred polymers include a first type of moiety which is relativelydifficult to sulphonate and a second type of moiety which is relativelyeasy to sulphonate. For example, said second moiety may be sulphonatableusing the relatively mild method described in Example 13 hereinafter,whereas the first moiety may be substantially non-sulphonatable in sucha method. The use of the method of Example 13 may be advantageous overcurrently used methods which use oleum. A preferred second said moietyincludes a imoiety —Ph_(n)— wherein n is an integer of at least 2. Saidmoiety is preferably bound to at least one ether oxygen. Especiallypreferred is the case wherein said moiety is —O—Ph_(n)—O— where saidether groups are para to the Ph—Ph bond.

Preferred polymers are copolymers comprising a first repeat unit whichis selected from the following:

(a) a unit of formula IV wherein E and E′ represent oxygen atoms, Grepresents a direct link, Ar represents a moiety of structure (iv), mand s represent zero, w represents 1 and A and B represent 1;

(b) a unit of formula IV wherein E represents an oxygen tom, E′represents a direct link, Ar represents a moiety of structure (i), mrepresents zero, A represents 1, B represents zero;

(c) a unit of formula V wherein E and E′ represent oxygen atoms, Grepresents a direct link, Ar represents a moiety of structure (iv), mand v represent zero, z represents 1 and C and D represent 1;

(d) a unit of formula V wherein E represents an oxygen atom, E′represents a direct link, Ar represents a moiety of structure (ii), mrepresents 0, C represents 1, D represents 0; or

(e) a unit of formula V wherein E and E′ represents an oxygen atom, Arrepresents a structure (i), m represents 0, C represents 1, Z represents1, G represents a direct link, v represents 0 and D represents 1;

and a second repeat unit which is selected from the following:

(f) a unit of formula IV wherein E and E′ represent oxygen atoms, Grepresents a direct link, Ar represents a moiety of structure (iv), mrepresents 1, w represents 1, s represents zero, A and B represent 1;

(g) a unit of formula IV wherein E represents an oxygen atom, E′ is adirect link, G represents a direct link, Ar represents a moiety ofstructure (iv), m and s represent zero, w represent 1, A and B represent1;

(h) a unit of formula V wherein E and E′ represent oxygen atoms, Grepresents a direct link, Ar represents a moiety of structure (iv), mrepresents 1, z represents 1, v represents 0, C and D represent 1; and

(i) a unit of formula V wherein E represents an oxygen atom, E′represents a direct link, G represents a direct link, Ar represents amoiety of structure (iv), mland v represent zero, z represents 1, C andD represent 1;

Other second units which may form copolymers with any of said firstrepeat units (a) to (e) above include: a unit of formula IV wherein Eand E′ represent oxygen atoms, G represents a direct link, Ar representsa moiety of structure (v), m represents 0, w represents 1, s represents0, A and B represent 1; or a unit of formula V wherein E and E′represent oxygen atoms, G represents a direct link, Ar represents amoiety of structure (v), m represents: 0, z represents 1, v represents0, C and: D represent 1.

Preferred polymers for some situations may comprise first units selectedfrom (a), (b), (c) and (e) and second units selected from (f), (g), (h)or (i). A polymer. comprising units (d) and (h) may also be preferred.

More preferred polymers are copolymers having a first repeat unitselected from those described above, especially repeat units (b), (d) or(e) in combination with a second repeat unit selected from units (f) or(h).

Preferred polymers having repeat unit(s) of formulae IV* and V* mayinclude: a unit of formula IV* wherein Ar represents a moiety ofstructure (v), E represents a direct link, E′ represents an oxygen atom,G represents a direct link, w, s and m represent 0, A and B represent 1;and/or a repeat unit of formula. V* wherein Ar represents a moiety ofstructure (v), E represents a direct link, E′ represents an oxygen atom,G represents a direct link, z, v and m represent 0, C and D represent 1.

Said polymers having repeat units IV* and V* may include any of repeatunits (a) to (i) described above.

In some situations, polymers which include at least one repeat unit offormula IV or formula IV* may be preferred.

Copolymers may be prepared having one or more first repeat units and oneor more of said second repeat units.

Where said polymer is a copolymer as described, the mole % of co-monomerunits, for example said first and second repeat units described above,may be varied to vary the solubility of the polymer in solvents, forexample in organic solvents which may be used in the preparation offilms and/or membranes from the polymers and/or in other solvents,especially water.

Preferred polymers suitably have a solubility of at least 10% w/v,preferably a solubility in the range 10 to 30% w/v in a polar aproticsolvent, for example NMP, DMSO or DMF. Preferred polymers aresubstantially insoluble in boiling water.

First units of the type described above (with, the exception of units(a) and (c)) may be relatively difficult to sulphonate, whereas secondunits of the type described may be easier to sulphonate.

Where a phenyl moiety is sulphonated, it may only be mono-sulphonated.However, in some situations it may be possible to effect bi- ormulti-sulphonation.

In general terms, where a said polymer includes a —O-phenyl-O— moiety,up to 100 mole % of the phenyl moieties may be sulphonated. Where a saidpolymer includes a —O-biphenylene-O— moiety, up to 100 mole % of thephenyl moieties may be sulphonated. It is believed to be possible tosulphonate relatively easily —O-(phenyl)_(n)—O— moieties wherein n is aninteger, suitably 1-3, at up to 100 mole %. Moieties of formula—O-(phenyl)_(n)—CO— or —O-(phenyl)_(n)—SO₂— may also be sulphonated atup to 100 mole % but more vigorous conditions may be required. Moietiesof formulae —CO-(phenyl)_(n)—CO— and —SO₂-(phenyl)_(n)—SO₂— are moredifficult to sulphonate and may be sulphonated to a level less than 100mole % or not at all under some sulphonation conditions.

The glass transition temperature (T_(g)) of said polymer may be at least144° C., suitably at least 150° C., preferably at least 154° C., morepreferably at least 160° C., especially at least 164° C. In some cases,the Tg may be at least 170° C., or at least 190° C. or greater than 250°C. or even 300° C.

Said polymer may have an inherent viscosity (IV) of at least 0.1,suitably at least 0.3, preferably at least 0.4, more preferably at least0.6, especially at least 0.7 (which corresponds to a reduced viscosity(RV) of least 0.8) wherein RV is measured at 25° C. on a solution of thepolymer in concentrated sulphuric acid of density 1.84 gcm⁻³, saidsolution containing 1 g of polymer per 100 cm⁻³ of solution. IV ismeasured at 25° C. on a solution of polymer in concentrated sulphuricacid of density 1.84 gcm³, said solution containing 0.1 g of polymer per100 cm³ of solution.

The measurements of both RV and IV both suitably employ a viscometerhaving a solvent flow time of approximately 2 minutes.

The main peak of the melting endotherm (Tm) for said polymer (ifcrystalline) may be at least 300° C.

In general terms, said polymer is preferably substantially stable whenused as a PEM in a fuel cell. Thus, it suitably has high resistance tooxidation, reduction and hydrolysis and has very low permeability toreactants in the fuel cell. Preferably, however, it has a high protonconductivity. Furthermore, it suitably has high mechanical strength andis capable of being bonded to other components which make up a membraneelectrode assembly.

Said polymer may comprise a film, suitably having a thickness of lessthan 1 mm, preferably less than 0.5 mm, more preferably less than 0.1mm, especially less than 0.05 mm. The film may have a thickness of atleast 5μm.

Said polymer electrolyte membrane may comprise one or more layerswherein, suitably, at least one layer comprises a film of said polymer.Said membrane may have a thickness of at least 5μm and, suitably, lessthan 1 mm, preferably less than 0.5 mm, more preferably less than 0.1mm, especially less than 0.05 mm.

The polymer electrolyte membrane may be a composite membrane whichsuitably includes a support material for the conductive polymer forimporting mechanical strength and dimensional stability to the membrane.The polymer may be associated with the support material to form acomposite membrane in a variety of ways. For example, an unsupportedconductive polymer film can be preformed and laminated to the supportmaterial. Alternatively, (and preferably) the support material may beporous and a solution of the conductive polymer can be impregnated intothe support material. In one embodiment, the support material maycomprise, or preferably consist essentially of, polytetrafluoroethylene,suitably provided as a porous film. Such a support material may be asdescribed and used in accordance with the teachings of WO97/25369andWO96/28242, the contents of which are incorporated herein by reference.Suitably, the support material has a porous microstructure of polymericfibrils and is impregnated with said polymer throughout the material,preferably so as to render an interior volume of the membranesubstantially occlusive.

The use of support material as described may allow polymers of lowerequivalent weights (EW) (for example less than 500 g/mol, less than 450g/mol or even less than 400 g/mol or 370 g/mol) or relatively inflexibleand/or brittle polymers to be used in polymer electrolyte membranes.

The polymer electrolyte membrane suitably includes a layer of a catalystmaterial, which may be a platinum catalyst (i.e. platinum containing) ora mixture of platinum and ruthenium, on both sides of the polymer film.Electrodes may be provided outside the catalyst material.

It may be preferable for each phenyl group in a sulphonated polymer asdescribed to be deactivated by being bonded directly to an electronwithdrawing group, for example a sulphonated group, a sulphone group ora ketone group.

According to a second aspect of the invention, there is provided apolymer electrolyte membrane which includes a polymer which includes:polyaryletherketone and/or polyarylethersulphone units; and units offormula —OPh_(n)—O— (XX) wherein Ph represents a phenyl group and nrepresents an integer of 2 or greater and wherein Ph groups of units(XX) are sulphonated.

Preferably, each phenyl group of moiety Ph_(n) is sulphonated,preferably mono-sulphonated. About 100 mole % of such phenyl groups maybe sulphonated as described.

Preferably, —OPhCO— and/or —OPhSO₂— moieties of said polymer aresulphonated to a lesser extent than the phenyl groups of moiety Ph_(n).Moieties —OPhCO— and —OPhSO₂— may be substantially non-sulphonated.

In one embodiment, said polymer may include no ketone linkages and mayhave an equivalent weight of more than 900. Nonetheless, it has beenfound, surprisingly, that such polymers are still conducting.

Said polymer electrolyte membrane may be for a fuel cell or anelectrolyser.

The invention extends to the use of a polymer which includes relativelyeasy to sulphonate units and relatively difficult to sulphonace units inthe preparation of a polymer for a polymer electrolyte membrane.

The polymer electrolyte membrane described herein may include a blend ofpolymers, at least one of which is a polymer described according to theinvention described herein. Suitably the polymers described herein areblended with 0-40wt %, preferably 0-20wt %, more preferably 0-10wt %,especially 0—5wt % of other polymeric material. Preferably, however, ablend of polymers is not provided.

According to a third aspect of the invention, there is provided a fuelcell or an electrolyser (especially a fuel cell) incorporating a polymerelectrolyte membrane according to the first or second aspects.

According to a fourth aspect of the invention, there is provided anynovel polymer as described according to said first aspect per se.

According to a fifth aspect of the invention, there is provided aprocess for the preparation of a polymer as described in the first,second, third and/or fourth aspects, the process comprising:

(a) polycondensing a compound of general formula

with itself wherein Y¹ represents a halogen atom or a group —EH and y²represents a halogen atom or, if y¹ represents a halogen atom, Y²represents a group E′H; or

(b) polycondensing a compound of general formula

with a compound of formula

and/or with a compound of formula

wherein Y¹ represents a halogen atom or a group —EH (or E′ H ifappropriate) and X¹ represents the other one of a halogen atom or group—EH (or —E′H if appropriate) and Y² represents a halogen atom or a group—E′ H and X² represents the other one of a halogen atom or a group —E′ H(or —EH if appropriate).

(c) optionally copolymerizing a product of a process as described inparagraph (a) with a product of a process as described in paragraph (b);

wherein the phenyl moieties of units VI, VII and/or VIII are optionallysubstituted; the compounds VI, VII and/or VIII are optionallysulphonated; and Ar, m, w, r, s, z, t, v, G, E and E′ are as describedabove except that E and E′ do not represent a direct link;

the process also optionally comprising sulphonating and/or cross-linkinga product of the reaction described in paragraphs (a), (b) and/or (c) toprepare said polymer.

In some situations, the polymer prepared, more particularly phenylgroups thereof, may be optionally substituted with the groupshereinabove described after polymer formation.

Preferably, where Y¹, Y², X¹ and/or X² represent a halogen, especially afluorine, atom, an activating group, especially a carbonyl or sulphonegroup, is arranged ortho- or para- to the halogen atom.

Advantageously, where it is desired to prepare a copolymer comprising afirst repeat unit IV or V wherein E represent an oxygen or sulphur atom,Ar represents a moiety of structure (i), m represents zero, E′represents a direct link, A represents 1 and B represents zero and asecond repeat unit IV or V wherein E and E′ represent an oxygen orsulphur atom, Ar represents a moiety of structure (iv), m and wrepresent 1, G represents a direct link, s represents zero and A and Brepresent 1 wherein the polymer is not a random polymer but has aregular structure, the process described in paragraph (b) above may beused wherein in said compound of general formula VI, Y¹ and y2 represent—OH or —SH groups, Ar represents a moiety of structure (iv) and mrepresents 1 and in said compounds of general formulae VII and VIII, X¹and X² represent a fluorine atom, w,r,s,z,t and v represent 1 and Grepresents an oxygen or sulphur atom.

In another embodiment, where it is desired to prepare a copolymercomprising a first repeat unit IV or V wherein E and E′ represent anoxygen or sulphur atom, Ar represents a moiety of structure (iv), mrepresents zero, A represents 1, w represents 1, s represents zero and Brepresents: 1 and a second repeat unit IV or V wherein E and E′represent an oxygen or sulphur atom, Ar represents a moiety of structure(iv), m and w represent 1, s represents zero and A and B represent 1,wherein the polymer is not a random polymer but has a regular structure,the process described in paragraph (b) above may be used wherein in saidcompound of general formula VI, Y¹ and Y² represent —OH or —SH groups,Ar represents a moiety of structure (iv) and m represents 1 and in saidcompounds of general formulae VII and VIII, X¹ and X² represent afluorine atom, w,r,s,z,t and v represent 1 and G represents a —O—Ph—O—moiety.

Preferred halogen atoms are fluorine and chlorine atoms, with fluorineatoms being especially preferred. Preferably, halogen atoms are arrangedmeta- or para- to activating groups, especially carbonyl groups.

Where the process described in paragraph (a) is carried out, preferablyone of Y¹ and Y² represents a fluorine atom and the other represents anhydroxy group. More preferably in this case, Y¹ represents a fluorineatom and Y² represents an hydroxy group. Advantageously; the processdescribed in paragraph (a) may be used when Ar represents a moiety ofstructure (i) and m represents 1.

When a process described in paragraph (b) is carried out, preferably, Y¹and Y² each represent an hydroxy group. Preferably, X¹ and X² eachrepresent a halogen atom, suitably the same halogen atom.

Compounds of general formula VI, VII and VIII are commercially available(eg from Aldrich U.K.) and/or may be prepared by standard techniques,generally involving is Friedel-Crafts reactions, followed by appropriatederivatisation of functional groups. The preparations of some of themonomers described herein are described in P M Hergenrother, B J Jensenand S J Havens, Polymer 29, 358 (1998), H R Kricheldorf and U Delius,Macromolecules 22, 517 (1989) and P A Staniland, Bull, Soc, Chem, Belg.,98 (9-10), 667 (1989)

Where compounds VI, VII and/or VIII are sulphonated, compounds offormulas VI, VII and/or VIII which arel not sulphonated may be preparedand such compounds may be sulphonated prior to said polycondensationreaction.

Sulphonation as described herein may be carried oust in concentratedsulphuric acid (suitably at least 96% w/w, preferably at least 97% w/w,more preferably at least 98% w/w; and preferably less than 98.5% w/w) atan elevated temperature. For example, dried polymer may be contactedwith sulphuric acid and heated with stirring at a temperature of greaterthan 40° C., preferably greater than 55° C., for at least one hour,preferably at least two hours, more preferably about three hours. Thedesired product may be caused to precipitate, suitably by contact withcooled water, and isolated by standard techniques. Sulphonation may alsobe effected as described in U.S. Pat. No. 5,362,836 and/or EP0041780.

Where the process described in paragraph (b) is carried out, suitably,“a*” represents the mole % of compound VI used in the process; “b*”represents the mole % of compound VII used in the process; and “c*”represents the mole % of compound VIII used in the process.

Preferably, a* is in the range 45-55, especially in the. range 48-52.Preferably, the sum of b* and c* is in the range 45-55, especially inthe range 48-52. Preferably, the sum of a*, b* and c* is 100.

Where the process described in paragraph (b) is carried out, preferably,one of either the total mole % of halogen atoms or groups —EH/—E′H incompounds VI, VII and VIII is greater, for example by up to 10%,especially up to 5%, than the total mole % of the other one of eitherthe total mole % of halogen atoms or groups —EH/—E′H in compounds VI,VII and VIII. Where the mole % of halogen atoms is greater, the polymermay have halogen end groups and be more stable than when the mole % ofgroups —EH/—E′H is greater in which case the polymer will have —EH/—E′Hend groups. However, polymers having —EH/—E′H end groups may beadvantageously cross-linked.

The molecular weight of the polymer can also be controlled by using anexcess of halogen or hydroxy reactants. The excess may typically be inthe range 0.1 to 5.0 mole %. The polymerisation reaction may beterminated by addition of one or more monofunctional reactants asend-cappers.

It is believed that certain polymers described herein are novel and,therefore, in a sixth aspect, the invention extends to any novel polymerdescribed herein per se.

It is also believed that certain polymers according to said first and/orsecond aspect but which are; not sulphonated are novel. Thus, accordingto a seventh aspect of the invention, there is provided a novel polymerhaving a moiety of formula I and/or a moiety of formula II and/or amoiety of formula III wherein ,E,E′, G,m,r,s,t,v,w,z and Ar are asdescribed in any statement herein.

Preferably, said polymer includes a moiety of formula II and/or III andAr is selected from

Preferably, in the aforementioned formulae, each —Ar— is bonded toadjacent moieties as described in any statement herein.

According co an eighth aspect of the invention, there is provided aprocess for the preparation of novel polymers according to said seventhaspect, the process being as described according to the process of thefifth aspect except that compounds VI, VII and VIII are not sulphonatedand the process does not include a sulphonation step.

Sulphonated polymers described herein may be made into films and/ormembranes for use as PEMs by conventional techniques, for example asdescribed in Examples 5 to, 7 of U.S. Pat. No. 5,561,202.

The sulphonated polymers described herein may be used as polymerelectrolyte membranes in fuel cells or electrolysers as described.Additionally, they may be used in gas diffusion electrodes.

Any feature of any aspect of any invention or example described hereinmay be combined with any feature of any aspect of any other invention orexample described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

Specific embodiments of the invention will now be described, by way ofexample, with reference to FIG. 1 which is a schematic representation ofa polymer electrolyte membrane fuel cell.

As described above, the fuel cell includes a thin sheet 2 of ahydrogen-ion conducting Polymer Electrolyte Membrane. The preparation ofsheet material for such a membrane is described hereinafter.

EXAMPLES Example 1

A 700 ml flanged flask fitted with a ground glass Quickfit lid,stirrer/stirrer guide, nitrogen inlet and outlet was charged with4,4′-difluorobenzophenone (891.03 g, 0.408 mole),4,41′-dihydroxybenzophenone (34.28 g, 0.16 mole),4,4′-dihydroxybiphenyl(44.69 g, 0.24 mole): and diphenysulphone (332 g)and purged with nitrogen for at least 1 hour. The contents were thenheated under a nitrogen blanket to between 140 and 145° C. to form analmost colourless solution. While maintaining a nitrogen blanket, driedsodium carbonate (43.24 g, 0.408 mole) was added. The temperature wasraised gradually to 335° C. over 200 minutes then maintained for 1 hour.

The reaction mixture was allowed to cool, milled and washed with acetoneand water. The resulting polymer, was dried in an air oven at 120° C.The polymer had a Tg of 164° C., a melt viscosity at 400° C., 1000 sec⁻¹of 0.48 kNsm⁻² and an inherent viscosity (IV) 0.40 (measured at 25° C.on a solution of the polymer in concentrated sulphuric acid of density1.84 g.cm⁻³, said solution containing 0.1g of polymer/100 cm³)

Examples 2 to 6.

The polymerisation procedure of Example 1 was followed, except thatcopolymers of different compositions were prepared by varying the moleratios of 4,4′-dihydroxybenzophenone to 4,4′,-dihydroxybiphenyl, withthe sum of the number of moles of the aforesaid reactants equalling thenumber of moles of 4,4′-difluorobenzophenone, as described in Example 1.A summary of the mole ratios and the MV are detailed in the table below.

4,4′ dihydroxybiphenyl: 4,4′- Example No dihydroxybenzophenoneMV(kNsm⁻²) 2 2:1 0.17 3a 1:1 0.48 3b* 1:1 0.69 4 1:2 0.54 5 1:3 0.43 61.25:1   0.34 *The polymerisation procedure of Example 1 was followedexcept dried sodium carbonate (43.24 g, 0.408 mole) was replaced bydried sodium carbonate (42.44 g, 0.4 mole) and dried potassium carbonate(1.11 g, 0.008 mole).

The polymerisation procedure of Example 1 was followed except driedsodium carbonate (43.24 g, 0.408 mole) was replaced by dried sodiumcarbonate (42.44 g, 0.4 mole) and dried potassium carbonate (1.11 g,0.008 mole).

Example 7a

A 700 ml flanged flask fitted with a ground glass Quickfit lid,stirrer/stirrer guide, nitrogen inlet and outlet was charged with4,4′-difluorobenzophenone (89.03 g, 0.408 mole), 4,4′-dihydroxybiphenyl(37.24 g, 0.2 mole) 4,4′-oxydiphenylsulphone (50.05 g, 0.2 mole), anddiphenysulphone (332 g) and purged with nitrogen for over 1 hour. Thecontents were then heated under a nitrogen blanket to between 140 and150° C. to form an almost colourless solution. While maintaining anitrogen blanket, dried sodium carbonate (42.44 g, 0.4 mole) andpotassuim carbonate (1.11 g, 0.008 mole) were added. The temperature wasraised gradually to 315° C. over 3 hours then maintained for 0.5 hours.

The reaction mixture was allowed to cool, milled and washed with acetoneand water. The resulting polymer was dried in an air oven at 120° C. Thepolymer had a Tg of 183° C., a melt viscosity at 400° C, 1000 sec⁻¹ of0.78 kNsm⁻² and an inherent viscosity (IV) 0.40 (measured at 25° C. on asolution of the polymer in concentrated sulphuric acid of density 1.84g.cm⁻³, the solution containing 0.1 g of polymer/100cm³)

Example 7b

The polymerisation procedure of Example 7a was followed except driedsodium carbonate (42.44 g, 0.4 mole) and dried potassium carbonate (1.11g, 0.008 mole) was replaced by dried sodium carbonate only (43.24 g,0.408 mole). The polymer had a Tg of 183° C. and a melt viscosity at400° C., 1000 sec⁻¹ of 0.43 kNsm⁻²

Examples 8 and 10

The polymerisation procedure of Example 7b was followed, except thatcopolymers were prepared by varying the mole ratios of thehydroxy-containing reactants, with the sum of the number of moles of theaforesaid equalling the number of moles of 4,4′-difluorobenzophenone. Asummary of the mole ratios and the MV are detailed in the table below.

4,4′-dihydroxybiphenyl:4,4′- Example No dihydroxydiphenyl-sulphoneMV(kNsm⁻²) 8 1:2 0.67 9 1:3 0.72 10 1:1.5 0.6

Example 11

A 700 ml flanged flask fitted with a ground glass Quickfit lid,stirrer/stirrer guide, nitrogen inlet and outlet was charged with4,4′-dichlorodiphenylsulphone (104.25 g, 0.36 mole),4,4′-dihydroxydiphenylsulphone (6.75 g, 0.27 mole),4,4′-dihydroxybiphenyl (16.74 g, 0.09 mole) and diphenysulphone (245 g)and purged with nitrogen for at least 1 hour. The contents were thenheated under a nitrogen blanket to between 140 and 145° C. to form analmost colourless solution. While maintaining a nitrogen blanketpotassium carbonates (50.76 g, 0.37 mole), was added. The temperaturewas raised to 180° C., held for 0.5 hours, raised to 205° C., held for 1hour, raised to 225° C., held for 2 hours, raised to 265° C., held for0.5 hours, raised to 280° C. and held for 2 hours.

The reaction mixture was allowed to cool, milled and washed withacetone/methanol (30/70) and water. The resulting polymer was dried inan air oven at 120° C.

Example 12

The polymerisation procedure of Example 11 was followed, except that theratio of 4,4′-dihydroxybiphenyl to 4,4′-dihydroxydiphenylsulphone was1:2. The polymer has a Tg of 198° C. and on RV of 0.52.

Example 13 Sulphonation of Polymers of Example 1 to 12

The polymers of Examples 1 to 12 were sulphonated by stirring eachpolymer in 98% sulphuric acid (3.84 g polymer/100 g sulphuric acid) for21 hours at 50° C. Thereafter, the reaction solution was allowed to dripinto stirred deionised water. Sulphonated polymer precipitated asfree-flowing beads. Recovery was by filtration, followed by washing withdeionised water until the pH was neutral and subsequent drying. Ingeneral, ¹H nmr in DMSO—d6 confirmed that 100 mole % of the biphenylunits had sulphonated, giving one sulphonic acid group, ortho to theether linkage, on each of the two aromatic rings comprising the biphenylunit. For examples 3 to 5, 100% sulphonation of —O—Ph—Ph—O— moieties wasconfirmed by, converting the sulphonated ionomer from the H⁺ form to Na⁺form, by reacting 0.5 g of the dry sulphonated copolymer with an aqueoussolution of NaOH (2.5 g NaOH/200 ml water) at 60-65° C. for 2 hours thenwashing the product with water and drying at 60° C., followed by sodiumanalysis.

Example 14 Membrane Fabrication

Membranes were produced from selected polymers off Examples 1 to 12after sulphonation as described in Example 13 by dissolving respectivepolymers in N-methylpyrrolidone (NMP). The polymers were dissolved at aconcentration of 15% wt/v, except for Examples 3a and 6 which weredissolved to 4% wt/v. The homogeneous solutions were cast onto cleanglass plates and then drawn down to give 300 micron films, using astainless steel Gardner Knife. Evaporation at 100° C. under vacuum for24 hours produced membranes of mean thickness 40 microns except thatExamples 3a and 6 produced membranes of about 10 microns.

Example 15 Water-uptake of the Membranes

5 cm×5 cm×40 microns samples of membranes of Example 14 were immersed indeionized water (500 ml) for 3 days, dried quickly with lint-free paperto remove surface water and weighed, dried in an oven at 50° C. for 1day, allowed to cool to ambient temperature in a desiccator then weighedquickly.

The water uptake was measured as follows, with the results beingprovided in the table below. “Equivalent weight” is defined as theweight of polymer containing unit weight of replaceable acidic hydrogen.

${\% \quad {Water}\quad {Up}\text{-}{take}} = {\frac{{{Wet}\quad {Weight}} - {{Dry}\quad {Weight}}}{{Dry}\quad {Weight}} \times 100}$

Membrane prepared from sulphonated polymer of Equivalent Weight ExampleNo: (g/mol) % Water Up-take  2 360 136.4 3a 458 54.4  6 419 69.3 7a 47661.5  8 690 30.5  9 904 21.9 10 583 38.7 11 976 21.6 12 744 30.7

Example 16 Performance of Membranes a Polymer Membrane Fuel Cell

The membranes prepared from sulphonated polymers of Examples 8 to 11were installed in a Standard PEMFC single cell test module andpolarisation date was generated and compared to Nafion 115, a leadingcommercially-available membrane. The current densities obtained at 0.8 Vwere 0.42, 0.58 and 0.26Acm⁻² for the Example 8 to 11 polymersrespectively, compared to 0.12 Acm⁻² for Nafion 115.

Example 17

The S number of a polymer is defined as follows:${S\quad {Number}} = \frac{{Number}\quad {of}\quad {unsulphonated}\quad {phenyls}}{{Number}\quad {of}\quad {sulphonated}\quad {phenyls}}$

The S number for polymers described above is summarised in the tablebelow.

Example No. S Number 1 2.33 2 2 3 3 4 5 5 7 6 2.6 7a 3 8 5 9 7 10 4 11 712 5

Example 18

A 500 ml, 3-necked round-bottomed flask fitted with a stirrer, nitrogeninlet and air condenser was charged with 4,4′-difluorobenzophenone(35.79 g, 0.164 mole), hydroquinone (11.01 g, 0.10 mole),4,4′-dihydroxybiphenyl (18.62 g, 0.10 mole),4,4′-bis(4-chlorophenylsulphonyl)biphenyl (LCDC) (20.13 g, 0.04 mole)and diphenylsulphone (202.76 g) and the contents were heated under anitrogen blanket to 160° C. to form a nearly colourless solution. Whilemaintaining a nitrogen blanket, anhydrous potassium carbonate (29.02 g,0.21 mole) was added and the mixture stirred for 35 minutes. Thetemperature was raised gradually to 220° C. over 2 hours then raised to280° C. over 2 hours and maintained for 2 hours.

The reaction mixture was allowed to cool, milled and washed withacetone/methanol and water. The resulting solid polymer was dried at140° C. under vacuum. The polymer had a reduced viscosity of (RV) 2.50(measured at 25° C. on a solution of the polymer in concentratedsulphuric acid of density 1.84 g.cm⁻³, said solution containing 1 g ofpolymer/100 cm⁻³) and a Tg of 186° C.

Example 19

A 250 ml, 3-necked round-bottomed flask fitted with stirrer, nitrogeninlet and air condenser was charged with 4,4′-difluorobenzophenone(33.06 g, 0.1515 mole), hydroquinone (13.21g, 0.12 mole), 9, 9′-bis(4-hydroxyphenyl)fluorene(HPF) (10.512 g, 0.03 mole); anddiphenylsulphone (100.93 g) and the contents were heated under anitrogen blanket to 150®C. to form a nearly colourless solution. Whilemaintaining a nitrogen blanket, anhydrous potassium carbonate (21.77 g,0.15751 mole) was added. The temperature was raised to 175° C.maintained for 2 hours, raised to 200° C. maintained for 50 minutes,raised to 250° C. maintained for 45 minutes, raised to 300° C.maintained for 90 minutes.

The reaction mixture was allowed to cool, milled and washed withacetone/methanol and water. The resulting solid polymer was dried at140° C. under vacuum. The polymer had an reduced viscosity (RV) of 0.76(measured at 25° , PC on a solution of the polymer in concentratedsulphuric acid of density 1.84 g.cm⁻³, said solution containing 1 g ofpolymer/100 cm⁻³) and a Tg of 165° C.

Example 20

A 250 ml, 3-necked round-bottomed flask fitted with a stirrer, nitrogeninlet and air condenser was charged with4,4′-bis(4-chlorophenylsulphonyl)-terphenyl (23.2 g, 0.04 mole),4,4′-dihydroxybiphenyl (7.44 g, 0.040 mole) and diphenylsulphone (80 g)and the contents were heated under a nitrogen blanket to 170° C. to forma nearly colourless solution. While maintaining a nitrogen blanket,anhydrous potassium carbonate (5.64 g, 0.408 mole) was added. Thetemperature was raised to 200° C. and maintained for 30 minutes, raisedto 250° C. and maintained for 15 minutes, raised to 275° C. andmaintained for 15 minutes, raised to 330° C. and maintained for 1 hour.

The reaction mixture was allowed to cool, milled and washed withacetone/methanol and water. The resulting solid polymer was dried at140° C. under vacuum. The polymer had an inherent viscosity (IV) of 0.50(measured at 25° C. on a solution of the polymer in concentratedsulphuric acid of density 1.84 g.cm⁻³, said solution containing 0.1 g ofpolymer/100 cm³) and a Tg of 264° C.

Example 21

A 250 ml, 3-necked round-bottomed flask fitted with a stirrer, nitrogeninlet and air condenser was charged with 4,4′-difluorobenzophenone(21.82 g, 0.10 mole), 4,4′-dihydroxybiphenyl (18.62 g, 0.10 mole) anddiphenylsulphone (60 g) and the contents were heated under a nitrogenblanket to 180° C. to form a nearly colourless solution. Whilemaintaining a nitrogen blanket anhydrous potassium carbonate (14.10 g,0.102 mole) was added. The temperature was raised to 200° C. over 60minutes, raised to 250° C. maintained for 5 mins, raised to. 325° C.maintained for 5 mins, raised to 370° C. over 90 mins, maintained for 10mins.

The reaction mixture was allowed to cool, milled and washed withacetone/methanol and water. The resulting solid polymer was dried at140° C. under vacuum. The polymer had an inherent viscosity (RV) of 1.28(measured at. 25° C. on a solution of the polymer in concentratedsulphuric acid of density 1.84 g.cm⁻³, said solution containing 1 g ofpolymer/100 cm³) and a Tg 167° C.

Example 22

A 250 ml, 3-necked round-bottomed flask fitted with a stirrer, nitrogeninlet and air condenser was charged with 4,4′-difluorobenzophenone(22.04 g, 0.101 mole), 4,4′-dihydroxybiphenyl (6.52 g, 0.035 mole),hydroquinone (,7.16 g, 0.065 mole) and diphenylsulphone (60 g) and thecontents were heated under a nitrogen blanket to 180° C. to form anearly colourless solution. While maintaining a nitrogen blanketanhydrous sodium carbonate (10.60 g, 0.100 mole) and anhydrous potassiumcarbonate (0.28 g, 0.002 mole) were added. The temperature was raised to200° C. held for 1 hour, raised to 250° C. held for 1 hour, raised to300° C. held for 1 hour. The reaction mixture was allowed to cool,milled and washed with acetone/methanol and water. The resulting solidpolymer was dried at 140° C. under vacuum. The polymer has an inherentviscosity (IV) 0.92 (measured at 25° C. on a solution of the polymer inconcentrated sulphuric acid of density 1.84 g.cm⁻³, said solutioncontaining 0.1 g of polymer/100 cm³) and a Tg 156° C.

Example 23

A 250 ml, 3-necked round-bottomed flask fitted width a stirrer, nitrogeninlet and air condenser was charged with4,4′-bis(4-fluorobenzoyl)diphenylether (21.34 g, 0.515 mole),4,4′-dihydroxybiphenyl (9.31 g, 0.050 mole) and diphenylsulphone (90 g)and the contents were heated under a nitrogen blanket to 160° C. to forma nearly colourless solution. While maintaining a nitrogen blanketanhydrous sodium carbonate (5.30 g, 0.050 mole) and anhydrous potassiumcarbonate (0.14 g, 0.001 mole) were added. The temperature was raised at1° C./min until it reached 345° C. and held for 1 hour.

The reaction mixture was allowed to cool, milled and washed withacetone/methanol and water. The resulting solid polymer was dried at140° C. under vacuum. The polymer had an inherent viscosity (RV) 1.48(measured at 25° C. on a solution of the polymer in concentratedsulphuric acid of density 1.84 g.cm³¹⁻³ said solution containing 1 g. ofpolymer/100 cm³) and a Tg 163° C.

Example 24 General procedure for Sulphonation of Polymers of Examples 18to 23

The polymers prepared as described in Examples 18 to 23 were sulphonatedaccording to the following procedure.

The dried polymer was placed in a three-necked round-bottomed flaskfitted with a stirrer containing 98% concentrated sulphuric acid (100cm³), heated with stirring to 60° C. and maintained at the temperaturefor 3 hours. The reaction product was poured into 5 litres of stirredice/water mixture. The product precipitated out. It was thenfiltered-off, washed with iced-water until the pH was neutral, washedwith methanol and dried under vacuum at 100° C. The degree ofsulphonation was determined by elemental analysis, filtration or Nmr.

Example 25 Sulphonation of Polymer of Example 22

The dried polymer from Example 22(10 g) was placed in a three-neckedround-bottomed flask fitted with a stirrer, containing 98% concentratedsulphuric acid (100 cm³), heated with stirring to 60° C. and maintainedat that temperature for 3 hours. The reaction products was poured into 5litres of stirred ice/water mixture. The product precipitated out, wasfiltered-off, washed with iced-water until the pH was neutral, washedwith methanol and dried under vacuum at 100° C. Nmr analysis showed thepolymer had readily sulphonated, in which 95-100 moles of theether-diphenyl-ether and ether-phenyl-ether units had been sulphonated.

Example 26

A 500 ml 3-necked round bottomed quickfit flask fitted withstirrer/stirrer guide, nitrogen inlet and outlet was is charged with4,4′-difluorobenzophenone (22.04 g, 0.102 mole),4,4′-dihydroxybenzophenone (10.71 g, 0.05 mole),2,7-dihydroxynaphthalene (8.01, 0.05 mole) and diphenyl sulphone (76.9g) and purged with nitrogen for at least 1 hour. The contents wereheated under a nitrogen blanket to about 132° C. to form a clearsolution. While maintaining a nitrogen blanket, dried sodium carbonate(10.81 g, 0.102 mole) was added. The temperature was raised gradually to290° C. over 240 minutes then maintained for 65 minutes.

The reaction mixture was allowed to cool, milled and washed with acetoneand water. The resulting polymer had a Tg of 158° C. and melt viscosityat 400° C., 1000 sec⁻¹ of 0.5 kNsm⁻².

The polymer was sulphonated using the process described in Example 13.The resultant sulphonated polymer has a water-uptake of 69.3% and anequivalent weight of 445.

The reader's attention is directed to all papers and documents which arefiled concurrently with or previous to this specification in connectionwith this application and which are open to public inspection with thisspecification, and the contents of all such papers and documents areincorporated herein by reference.

All of the features disclosed in this specification (including anyaccompanying claims, abstract and drawings), and/or all of the steps ofany method or process so disclosed, may be combined in any combination,except combinations where at least some of such features and/or stepsare mutually exclusive.

Each feature disclosed in this specification (including any accompanyingclaims, abstract and drawings), may be replaced by alternative featuresserving the same, equivalent or similar purpose, unless expressly statedotherwise. Thus, unless expressly stated otherwise, each featuredisclosed is one example only of a generic series of equivalent orsimilar features.

The invention is not restricted to the details of the foregoingembodiment(s). The invention extends to any novel one, or any novelcombination, of the features disclosed in this specification (includingany accompanying claims, abstract and drawings), or to any novel one, orany novel combination, of the steps of any method or process sodisclosed.

What is claimed is:
 1. A device selected from a fuel cell incorporatinga polymer electrolyte membrane, an electrolyser incorporating a polymerelectrolyte membrane and a gas diffusion electrode, wherein said polymerelectrolyte membrane or said gas diffusion electrode includes a polymerhaving a moiety of formula

and/or a moiety of formula

and/or a moiety of formula

wherein at least some of the units I, II, and/or III are sulphonated;wherein the phenyl moieties in units I, II and III are independentlyoptionally substituted and optionally cross-linked; and whereinm,r,s,t,v,w and z independently represent zero or a positive integer, Eand E′ independently represent an oxygen or a sulphur atom or a directlink, G represents an oxygen or a sulphur atom, a direct link or a—O—Ph—O— moiety where Ph represents a phenyl group and Ar is selectedfrom one of the following moieties (i) to (x) which is bonded via one ormore of its phenyl moieties to adjacent moieties, wherein said polymerincludes at least some ketone moieties in the polymeric chain andwherein said polymer includes a multi-phenylene moiety bonded to twooxygen atoms or a fused ring aromatic moiety bonded to two oxygen atoms:


2. A device selected from a fuel cell incorporating a polymerelectrolyte membrane, an electrolyser incorporating a polymerelectrolyte membrane and a gas diffusion electrode, wherein said polymerelectrolyte membrane or said gas diffusion electrode includes a polymerhaving a moiety of formula

and/or a moiety of formula

and/or a moiety of formula

wherein at least some of the units I, II, and/or III are functionalisedto provide ion exchange sites; wherein the phenyl moieties in units I,II and III are independently optionally substituted and optionallycross-linked; and wherein m,r,s,t,v,w and z independently represent zeroor a positive integer, E and E′ independently represent an oxygen or asulphur atom or a direct link, G represents an oxygen or a sulphur atom,a direct link or a —O—Ph—O— moiety where Ph represents a phenyl groupand Ar is selected from one of the following moieties (i) to (x) whichis bonded via one or more of its phenyl moieties to adjacent moieties,wherein said polymer includes at least some ketone moieties in thepolymeric chain and wherein said polymer includes a multi-phenylenemoiety bonded to two oxygen atoms or a fused ring aromatic moiety bondedto two oxygen atoms:


3. A device selected from a fuel cell incorporating a polymerelectrolyte membrane, an electrolyser incorporating a polymerelectrolyte membrane and a gas diffusion electrode, wherein said polymerelectrolyte membrane or said gas diffusion electrode includes a polymerhaving a moiety of formula

and/or a moiety of formula

and/or a moiety of formula

wherein at least some of the units I, II, and/or III are functionalisedto provide ion exchange sites; wherein the phenyl moieties in units I,II and III are independently optionally substituted and optionallycross-linked; and wherein m,r,s,t,v,w and z independently represent zeroor a positive integer, E and E′ independently represent an oxygen or asulphur atom or a direct link, G represents an oxygen or a sulphur atom,a direct link or a —O—Ph—O— moiety where Ph represents a phenyl groupand Ar is selected from one of the following moieties (i) to (x) whichis bonded via one or more of its phenyl moieties to adjacent moieties,wherein said polymer is crystalline:


4. A device according to claim 1, wherein “a” represents the mole % ofunits of formula I in said polymer; “b” represents the mole % of unitsof formula II in said polymer; and “c” represents the mole % of units offormula III in said polymer and wherein a is in the range 45-55 and thesum of b and c is in the range of 45-55.
 5. A device according to claim1, wherein said polymer consists essentially of moieties I, II and/orIII.
 6. A device according to claim 1, wherein said polymer is a randomor block copolymer having a first repeat unit of general formula

or of general formula

and a second repeat unit of general formula IV or V, wherein A, B, C andD independently represent 0 or
 1. 7. A device according to claim 6,wherein said polymer includes at least one repeat unit of formula IV. 8.A device according to claim 6, wherein said polymer is a copolymercomprising a first repeat unit of formula IV wherein E and E′ representoxygen atoms, G represents a direct link, Ar represents a moiety ofstructure (iv), m represents 1, w represents 1, s represents zero, A andB represent 1; and a second repeat unit of formula V wherein E and E′represent oxygen atoms, Ar represents a structure (i), m represents 0, Crepresents 1, z represents 1, G represents a direct link, v represents 0and D represents
 1. 9. A device according to claim 6, wherein saidpolymer is a copolymer comprising a first repeat unit of formula IV,wherein E and E′ represent oxygen atoms, G represents a direct link, Arrepresents a moiety of structure (iv), m represents 1, w represents 1, srepresents 0, A and B represent
 1. 10. A device according to claim 6,wherein said polymer is a copolymer comprising a first repeat unit offormula IV wherein E and E′ represent oxygen atoms, G represents adirect link, Ar represents a moiety of structure (iv), m represents 1, wrepresents 1, s represents 0, A and B represent 1; and a second repeatunit of formula IV wherein E represents an oxygen atom, E′ represents adirect link, Ar represents a moiety of structure (i), m represents zero,A represents 1, B represents
 0. 11. A device according to claim 6,wherein said polymer is a copolymer comprising a first repeat unit whichis either: (a′) of formula IV wherein E and E′ represent oxygen atoms, Grepresents a direct link, Ar represents a moiety of structure (iv), mand s represent zero, w represents 1 and A and B represent 1; or (b′) offormula IV wherein E represents an oxygen atom, E′ represents a directlink, Ar represents a moiety of structure (i), m represents zero, Arepresents 1, B represents zero; and a second repeat unit which iseither: (c′) of formula IV wherein E and E′ represent oxygen atoms, Grepresents a direct link, Ar represents a moiety of structure (iv), mrepresents 1, w represents 1, s represents zero, A and B represent 1; or(d′) of formula IV wherein E represents an oxygen atom, E′ is a directlink, G represents a direct link, Ar represents a moiety of structure(iv), m and s represent zero, w represents 1, A and B represent
 1. 12. Adevice according to claim 6, wherein said polymer has a repeat unitselected from (a′) of formula IV wherein E and E′ represent oxygenatoms, G represents a direct link, Ar represents a moiety of structure(iv), m and s represent zero, w represents 1 and A and B represent 1; or(b′) of formula IV wherein E represents an oxygen atom, E′ represents adirect link, Ar represents a moiety of structure (i), m represents zero,A represents 1, B represents zero; in combination with a repeat unit offormula IV wherein E and E′ represent oxygen atoms, G represents adirect link, Ar represents a moiety of structure (iv), m represents 1, wrepresents 1, s represents zero, A and B represent
 1. 13. A deviceaccording to claim 6, comprising a first repeat unit which is selectedfrom the following: (a) a unit of formula IV wherein E and E′ representoxygen atoms, G represents a direct link, Ar represents a moiety ofstructure (iv), m and s representizero, w represents 1 and A and Brepresent 1; (b) a unit of formula IV wherein E represents an oxygenatom, E′ represents a direct link, Ar represents a moiety of structure(i), m represents zero, A represents 1, B represents zero; (c) a unit offormula V wherein E and E′ represent oxygen atoms, G represents a directlink, Ar represents a moiety of structure (iv), m and v represent zero,z represents 1 and C and D represent 1; (d) a unit of formula V whereinE represents an oxygen atom, E′ , represents a direct link, Arrepresents a moiety of structure (ii), m represents 0, C represents 1, Drepresents 0; or (e) a unit of formula V wherein E and E represents anoxygen atom, Ar represents a structure (i), m represents 0, C represents1, Z represents 1, G represents a direct link, v represents 0 and Drepresents 1; and a second repeat unit which is selected from thefollowing: (f) a unit of formula IV wherein E and E′ represent oxygenatoms, G represents a direct link, Ar represents a moiety of structure(iv), m represents 1, w represents 1, s represents zero, A and Brepresent 1; (g) a unit of formula IV wherein E represents an oxygenatom, E′ is a direct link, G represents a direct link, Ar represents amoiety of structure (iv), m and is represent zero, w represent 1, A andB represent 1; (h) a unit of formula V wherein E and E′ represent oxygenatoms G represents a direct link, Ar represents a moiety of structure(iv), m represents 1, z represents 1, v represents 0, C and D represent1; and (i) a unit of formula V wherein E represents an oxygen atom, E′represents a direct link, G represents a direct link, Ar represents amoiety of structure (iv), m and v represent zero, z represents 1, C andD represent
 1. 14. A device according to claim 6, wherein said secondunit is selected from a unit of formula IV wherein E and E′ representoxygen atoms, G represents a direct link, Ar represents a moiety ofstructure (v), m represents 0, w represents 1, s represents 0, A and Brepresent 1; or a unit of formula V wherein E and E′ represent oxygenatoms, G represents a direct link, Ar represents a moiety of structure(v), m represents 0, z represents 1, v represents 0, c and drepresent
 1. 15. A device according to claim 12, wherein said copolymerhas a first repeat unit selected from units (b), (d) or (e) incombination with a second repeat unit selected from units (f) or (h).16. A device according to claim 1, wherein said polymer is a copolymerhaving a first repeat unit of general formula

or of general formula

and a second repeat unit of general formula IV* or V*, wherein A, B. Cand D independently represent 0 or
 1. 17. A device according to claim16, wherein said polymer includes: a repeat unit of formula IV* whereinAr represents a moiety of structure (v), E represents a direct link, E′represents an oxygen atom, G represents a direct link, w, s and mrepresent 0, A and B represent 1; and/or a repeat unit of formula V*wherein Ar represents a moiety of structure (v), E represents a directlink, E′ represents an oxygen atom, G represents a direct link, z, v andm represent 0, C and D represent
 1. 18. A device according to claim 17,which includes a repeat unit of formula IV* or V* and a unit selectedfrom the following: (a) a unit of formula IV wherein E and E′ representoxygen atoms, G represents a direct link, Ar represents a moiety ofstructure (iv), m and s represent zero, w represents 1 and A and Brepresent 1; (b) a unit of formula IV wherein E represents an oxygenatom, E′ represents a direct link, Ar represents a moiety of structure(i), m represents zero, A represents 1, B represents zero; (c) a unit offormula V wherein E and E′ represent oxygen atoms, G represents a directlink, Ar represents a moiety of structure (iv), m and v represent zero,z represents 1 and C and D represent 1; (d) a unit of formula V whereinE represents an oxygen atom, E′ represents a direct link, Ar representsa moiety of structure (ii), m represents 0, C represents 1, D represents0; (e) a unit of formula V wherein E and E′ represents an oxygen atom,Ar represents a structure (i), m represents 0, C represents 1, Zrepresents 1, G represents a direct link, v represents 0 and Drepresents 1; (f) a unit of formula IV wherein E and E′ represent oxygenatoms, G represents a direct link, Ar represents a moiety of structure(iv), m represents 1, w represents 1, s represents zero, A and Brepresent 1; (g) a unit of formula IV wherein E represents an oxygenatom, E′ is a direct link, G represents a direct link, Ar represents amoiety of structure (iv), m and s represent zero, w represent 1, A and Brepresent 1; (h) a unit of formula V wherein E and E′ represent oxygenatoms, G represents a direct link, Ar represents a moiety of structure(iv), m represents 1, z represents 1, v represents 0, C and D represent1; and (i) a unit of formula V wherein E represents an oxygen atom, E′represents a direct link, G represents a direct link, Ar represents amoiety of structure (iv), m and v represent zero, z represents 1, C andD represent
 1. 19. A device according to claim 1, wherein Ar is selectedfrom moieties (i), (ii), (iv) and (v).
 20. A device according to claim1, wherein said polymer includes a —O-biphenylene-O— moiety or a—O-naphthalene-O— moiety.
 21. A device according to claim 3, whereinsaid polymer includes at least some ketone moieties.
 22. A deviceaccording to claim 3, wherein said polymer is a random or blockcopolymer having a first repeat unit of general formula

or of general formula

and a second repeat unit of general formula IV or V, wherein A, B, C andD independently represent 0 or
 1. 23. A device according to claim 1,wherein said polymer has a glass transition temperature (Tg) of at least144° C.
 24. A device according to claim 1, wherein said glass transitiontemperature is at least 154° C.
 25. A device according to claim 1,wherein said polymer has an inherent viscosity of at least 0.3.
 26. Adevice according to claim 1, wherein said device is a fuel cell.
 27. Adevice selected from a fuel cell incorporating a polymer electrolytemembrane, an electrolyser incorporating a polymer electrolyte membraneand a gas diffusion electrode, wherein said polymer electrolyte membraneor said gas diffusion electrode includes a polymer which includes atleast some ketone moieties in the polymeric chain and includes amulti-phenylene moiety bonded to two oxygen atoms or a fused ringaromatic moiety bonded to two oxygen atoms, said polymer being made in aprocess comprising: (a) polycondensing a compound of general formula

with itself wherein Y¹ represents a halogen atom or a group —EH and Y²represents a halogen atom or, if Y¹ represents a halogen atom, Y²represents a group E′H; or (b) polycondensing a compound of generalformula

with a compound of formula

and or with a compound of formula

wherein Y′ represents a halogen atom or a group —EH (or —E′H ifappropriate) and Y² represents a halogen atom or a group —E′H and X²represents the other one of a halogen atom or a group —E′H (or EH ofappropriate); and (c) optionally copolymerizing a product of a processas described in paragraph (a) with a product of a process as describedin paragraph (b); wherein the phenyl moieties of units VI, VlI and/orVIII are optionally substituted; the compounds VI, VII and/or VIII areoptionally sulphonated; and Ar, m, w, r, s, z, t, v, G, E and E′ are asdescribed in claim 1, except that E and E′ do not represent a directlink; the process also optionally comprising sulphonating and/orcross-linking a product of the reaction described in paragraphs (a), (b)and/or (c)(to prepare said polymer.
 28. A process according to claim 27,wherein sulphonation is carried out in concentrated sulphuric acid at anelevated temperature.
 29. A process according to claim 28, wherein saidconcentrated sulphuric acid comprises less than 98.5% w/w of saidsulphuric acid.
 30. A copolymer having a first unit of general formula

or of general formula

and a second unit of general formula IV or V, wherein A, B, C and Dindependently represent 0 or 1; wherein at least some of units IV and Vare functionalised to provide ion-exchange sites; wherein phenylmoieties in IV and V are independently optionally-substituted andoptionally cross-linked; wherein m, r, s, t, v w and z independentlyrepresent zero or a positive integer, E and E′ independently representan oxygen or a sulphur atom or a direct link, G represents an oxygen ora sulphur atom, a direct link or a —O—Ph—O— moiety wherein Ph representsa phenyl groups and Ar is selected from one of the following moieties(i) to (x) which is bonded via one or more of its phenyl moieties toadjacent moieties, wherein said copolymer includes at least some ketonemoieties in the polymeric chain and wherein said polymer includes amulti-phenylene moiety bonded to two oxygen atoms or a fused ringaromatic moiety bonded to two oxygen atoms:


31. A copolymer according to claim 30, wherein at least its IV and V aresulphonated.
 32. A copolymer according to claim 30, wherein saidcopolymer includes a first repeat unit of formula IV, wherein E and E′represent oxygen atoms, G represents a direct link, Ar represents amoiety of structure (iv), m represents 1, w represents 1, s represents0, A and B represent
 1. 33. A copolymer according to claim 30, whereinsaid copolymer includes a second unit selected from a unit of formula IVwherein E and E′ represent oxygen atoms, G represents a direct link, Arrepresents a moiety of structure (v), m represents 0, w represents 1, srepresents 0, A and B represent 1; and a unit of formula V wherein E andE′ represent oxygen atoms, G represents a direct link, Arn represents amoiety of structure (v), m represents 0, z represents 1, v represents 6,c and d represent
 1. 34. A copolymer according to claim 30, wherein saidcopolymer includes a first repeat unit of formula IV wherein E and E′represent oxygen atoms, G represents a direct link, Ar represents amoiety of structure (iv) 1 m represents 1, w represents 1, s representszero, A and B represent 1; and a second repeat unit of formula V whereinE and E′ represent oxygen atoms, Ar represents a structure (i), mrepresents 0, C represents 1, z represents 1, G represents a directlink, v represents 0 and D represents
 1. 35. A copolymer according toclaim 30, wherein said copolymer includes a first repeat unit of formulaIV wherein E and E′ represent oxygen atoms, G represents a direct link,Ar represents a moiety of structure (iv), m represents 1, w represents1, s represents 0, A and B represent 1; and a second repeat unit offormula IV wherein E represents an oxygen atom, E′ represents a directlink, Ar represents a moiety of structure (i), m represents zero, Arepresents 1, B represents
 0. 36. A copolymer according to any of claims31 to 34, wherein at least some of units IV and V are sulphonated.
 37. Adevice according to claim 1, or claim 2, wherein said polymer iscrystalline.
 38. A polymer electrolyte membrane which includes a polymerhaving a moiety of formula:

and/or a moiety of formula

and/or a moiety of formula

wherein at least some of the units I, II, and/or III are sulphonated;wherein the phenyl moieties in units I, II and III are independentlyoptionally substituted and optionally cross-linked; and whereinm,r,s,t,v,w and z independently represent zero or a positive integer, Eand E′ independently represent an oxygen or a sulphur atom obr a directlink, G represents an oxygen or a sulphur atom, a direct link or a—O—Ph—O— moiety where Ph represents a phenyl group and Ar is selectedfrom one of the following i moieties (i) to (x) which is bonded via oneor more of its phenyl moieties to adjacent moieties, wherein saidpolymer includes at least some ketone moieties in the polymeric chainand wherein said polymer includes a multi-phenylene moiety bonded to twooxygen atoms or a fused ring aromatic moiety bonded to two oxygen atoms: